X-34: Demonstrating Reusable Launch Vehicle Technologies

X-34: Demonstrating Reusable Launch Vehicle Technologies

NASA’s X-34 technology demonstrator is a flying laboratory for technologies and operations applicable to future low-cost, reusable launch vehicles. It is one of a family of technology demonstrators aimed at lowering launch costs from $10,000 to $1,000 per pound.

On Aug. 28, 1996, NASA signed a contract now worth $85.7 million with Orbital Sciences Corp., of Dulles, Va., for X-34 design, development and test flights. The 50-month contract includes three flight test vehicles. NASA and other government agencies are spending an additional $16 million for wind tunnel testing, thermal protection systems, vehicle health monitoring, ground support, engine testing and flight support. Orbital has invested $10 million in corporate funds for modifications to its L-1011 carrier aircraft to accommodate the X-34. NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the program.

The suborbital technology demonstrator is 58.3 feet (17.77 meters) long. It has a 27.7-foot (8.44 meter) wingspan and stands 11.5 feet (3.5 meters) tall. It is designed to be air-launched from Orbital Sciences Corp.’s L-1011, a commercial jetliner originally modified to carry the company’s expendable Pegasus launch vehicle.

The X-34 will be dropped from the L-1011, ignite its engine, and fly a preprogrammed flight profile before making an automated approach and landing on a conventional runway – a first for an American launch system.

The X-34 is capable of flying up to eight times the speed of sound and reaching altitudes of approximately 50 miles. It will be a workhorse for testing high reliability, low-cost technologies and operations needed to develop and operate the next generation of space vehicles.

The X-34 is scheduled to make a total of 27 unpowered and powered flights during its test program, beginning in early 2000. Captive-carry flights to prove the airworthiness of the combined L-1011 and X-34 vehicles began in June 1999. The first X-34 vehicle, designated A-1A, will be used for a series of tow tests on the ground at NASA’s Dryden Flight Research Center, Edwards, Calif. The A-1A vehicle will then be used for a series of unpowered test flights. It will be released from Orbital Sciences Corp.’s L-1011 carrier aircraft over the Army’s White Sands Missile Range, N.M., and land on the Army runway.

At the same time, Orbital will complete assembly of the second X-34 flight vehicle, designated A-2. Its Fastrac rocket engine will be installed on the vehicle and test fired on the ground at Holloman Air Force Base, N.M., test facilities. After these ground test firings, the first series of powered flight tests of the X-34 will be conducted from, and land at, Dryden.

The first series of powered flights at Dryden will gradually expand the X-34’s flight envelope. Initial powered flights will be at speeds of about Mach 2.2–2.2 times the speed of sound – and then gradually increased to approximately Mach 5 over eight powered flights.

The A-2 vehicle then will be shipped to NASA’s Kennedy Space Center, Fla., for a second series of flight tests. These flights, which will reach speeds of up to approximately Mach 4.6, will demonstrate rapid turnaround flight operations required for reusable launch vehicles of the future. This series of seven flights will be conducted by flying an average of once every 14 days. One of these flights will demonstrate a 24-hour turnaround capability for the X-34.

The remainder of the test program, which involves the third X-34 vehicle, designated A-3, will be completed at Dryden. These test flights will expand the rocket plane’s performance to its maximum speed of up to Mach eight and altitudes up to 250,000 feet (76.2 kilometers), while also testing additional reusable launch vehicle technologies as carry-on experiments. The program plans to demonstrate a cost goal of $500,000 per flight.

The Marshall Center began environmental impact (EIS) studies in 1999 required for the test program. The plan includes California, New Mexico and Florida as reasonable alternative sites to carry out X-34 powered flights or flight testing of other NASA experimental vehicles at some time in the future. Other states involved in the EIS process are Nevada and Utah, which the X-34 would fly over during California-based test flights. Those states also are being evaluated as contingency landing sites. North and South Carolina are being evaluated for contingency landings for Florida-based flights. The final flight test plan will not be approved until the final Environmental Impact Statement and Record of Decision are issued.

The goal of the X-34 and NASA’s other advanced technology demonstrators is to dramatically increase reliability and lower the cost of putting payloads into space.

By reducing the transportation cost, a commercial reusable launch vehicle would create new opportunities for scientific, commercial and educational endeavors while significantly improving U.S. economic competitiveness in the world launch market. NASA will be a customer – not an operator – for a commercial reusable launch vehicle.

Key technologies initially planned for demonstration on the X-34 are: lightweight composite airframe structures that require little inspection; reusable composite propellant tanks, tank insulation and other propulsion components; advanced thermal protection systems capable of surviving subsonic flights through rain and fog; integrated (built-in) low-cost avionics, including differential Global Positioning System and Inertial Navigation System; integrated automated vehicle health monitoring and checkout; and a conformal air data system for flight control inputs that would replace traditional blade-like air data probes, unable to survive reentry temperatures.

Other capabilities to be demonstrated during the flights are safe abort and automatic landing techniques, and landing in 20-knot cross winds.

The X-34 will be powered by the reusable Fastrac engine, designed and developed by Marshall Center engineers and built by NASA's industry partners, including several small businesses.

The Fastrac is a single-stage engine that burns a mixture of liquid oxygen and kerosene. It took two-and-a-half years to design the engine in contrast to an average seven years for previous American rocket engines. It has significantly fewer parts than earlier engines.

The Fastrac provides 60,000 pounds of thrust (267,000 Newtons) for the X-34. Each engine will initially cost about $1.2 million – about one-fifth the cost of similar engines not designed for simplicity and low cost.

The X-34 industry team is led by Orbital Sciences Corp., Dulles, Va. Industry team members include Allied Signal Aerospace, Tempe, Ariz., responsible for control actuators and hydraulic pumps; Oceaneering Space Systems, Houston, Texas, maker of the thermal protection blankets; and Draper Laboratories, Cambridge, Mass., responsible for entry guidance and flight software. The government team, led by the Marshall Center, and their responsibilities, include: NASA’s Langley Research Center, Hampton, Va., wind tunnel testing and analysis; NASA’s Ames Research Center, Mountain View, Calif., rigid thermal protection system; NASA’s Dryden Flight Research Center, Edwards Air Force Base, Calif., flight testing support operations; NASA’s Glenn Research Center, Cleveland, Ohio, Integrated Vehicle Health Monitoring sensor network; NASA’s Kennedy Space Center, Fla., flight operation support; NASA’s Stennis Space Center, Miss., Fastrac engine testing; NASA’s Johnson Space Center, Houston, Texas, White Sands Test Facility management; NASA’s White Sands Test Facility, N.M., flight test operation support, ground support equipment support and LOX tank cleaning.

X-34 Specifications
Length: 58.3 feet

Wingspan: 27.7 feet

Weight unfueled: 18,000 pounds

Fuel: LOX/RP-1, 30,000 pounds

Main propulsion: 1 Marshall-designed Fastrac engine

Thrust: 60,000 pounds

Maximum speed: Mach 8

Maximum altitude: approximately 50 miles

All composite primary and secondary structure

Autonomous flight control, including approach and landing